var minPathSum = function(grid) {
const n = grid.length
const m = grid[0].length
for( let i =1; i<n;i++){
grid[i][0] += grid[i-1][0]
}
for(let j=1; j<m;j++){
grid[0][j] += grid[0][j-1]
}
for(let i=1; i<n;i++){
for(let j=1;j<m;j++){
grid[i][j] += Math.min(grid[i-1][j],grid[i][j-1])
}
}
return grid[n-1][m-1]
};